Extension and retraction arrangements

ABSTRACT

An extension and retraction arrangement for retaining a supported article, such as a monitor, in relation to a trolley structure that is retained for axial extension and retraction in relation to an elongate support arrangement. A support arm, which can be unitary, articulated, pivoting, or non-pivoting, can be coupled to the trolley structure. The trolley structure can have a centrally disposed alcove disposed inboard of first and second rail members of the elongate support arrangement. A subsurface enclosure can retain the rail members, and first and second doors can selectively close an aperture in a framework coupled adjacent to an end of the subsurface enclosure. Constant force springs can assist travel of the trolley structure and an arcuate braking member or compressing spring can provide a braking effect to the trolley structure.

PRIORITY INFORMATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/521,660, filed Jun. 14, 2004, and to U.S. Provisional PatentApplication No. 60/668,423, filed Apr. 5, 2005.

FIELD OF THE INVENTION

The present invention relates generally to systems for supportingarticles. More particularly, disclosed herein are systems andarrangements for enabling an adjustment of a supported article, such asa computer, computer monitor, or other computer component, between anextended configuration and a retracted configuration.

BACKGROUND OF THE INVENTION

Computers have become an integral part of our business and personallives. The presence of a computer monitor, a keyboard, or a laptop orother computer component has come to be seen as a necessary evil for theaccomplishment of one's daily tasks. With the computer componentsinherently come wires that further clutter work surfaces. Many computercomponents, particularly computer monitors, have achieved reduced size.However, when not in use, they remain as obstacles to the full usage ofa work surface and contribute to a utilitarian and often displeasingappearance of the work surface and the office in general. Further,continuous exposure leaves the computer components vulnerable not onlyto environmental conditions but also to tampering and theft,particularly as the components become smaller, lighter, and moreportable.

It would be advantageous, therefore, if one could enjoy full usage of acomputer, computer component, or other article when desired while beingable to make the article effectively disappear from a work surface whenits presence is no longer necessary. A number of talented inventors havesought to provide mechanisms for enabling a manipulation of a computeror computer component, such as a monitor, between use and storageconfigurations. To date, however, the proposed solutions of the priorart, such as those disclosed in U.S. Pat. No. 5,526,756 to Watson, U.S.Pat. No. 6,494,150 to Phoenix et al., and U.S. Pat. No. 6,733,094 toChang, have been bulky and inelegant, of limited effectiveness, andrelatively complex in structure and operation. Furthermore, prior artmechanisms and furniture have been ill equipped to accommodate oneanother.

SUMMARY OF THE INVENTION

With an appreciation for the state of the art summarized above, thepresent inventor set forth with the basic object of providing anarrangement for enabling the extension and retraction of a supportedarticle, such as a computer monitor, that overcomes the disadvantagesexhibited by the prior art while providing a number of previouslyunrealized advantages thereover.

A more particular object of the invention is to provide an extension andretraction arrangement that enables a supported article to be disposedin an extended position for full usage thereof and in a retracted andunobtrusive storage position.

Another particular object of embodiments of the invention is to enable asupported article to be extended and retracted smoothly and without riskof damage to the article or an inadvertent retraction thereof.

A further object of embodiments of the invention is to provide anextension and retraction arrangement that is reliable, efficient, andelegant in construction and operation.

These and in all likelihood further objects and advantages of thepresent invention will become obvious not only to one who reviews thepresent specification and drawings but also to those who have anopportunity to experience an embodiment of the systems and arrangementsdisclosed herein. However, it will be appreciated that, although theaccomplishment of each of the foregoing objects in a single embodimentof the invention may be possible and indeed preferred, not allembodiments will seek or need to accomplish each and every potentialadvantage and function. Nonetheless, all such embodiments should beconsidered within the scope of the present invention.

One will appreciate that the foregoing discussion broadly outlines themore important goals and features of the invention to enable a betterunderstanding of the detailed description that follows and to instill abetter appreciation of the inventor's contribution to the art. Beforeany particular embodiment or aspect thereof is explained in detail, itmust be made clear that the following details of construction andillustrations of inventive concepts are mere examples of the manypossible manifestations of the invention.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawing figures:

FIG. 1 is a perspective view of an extension and retraction arrangementpursuant to the invention disclosed herein in an extended configurationand retained in relation to a support structure;

FIG. 2 is a perspective view of the extension and retraction arrangementof FIG. 1 in a partially extended configuration;

FIG. 3 is a perspective view of the extension and retraction arrangementof FIG. 1 in a retracted configuration;

FIG. 4 is a perspective view of an extension and retraction arrangementas disclosed herein apart from a support structure;

FIG. 5 is a perspective view of a further extension and retractionarrangement pursuant to the present invention;

FIG. 6 is an exploded perspective view of an extension and retractionarrangement under the instant invention;

FIG. 7 is a cross sectional view of an extension and retractionarrangement pursuant to the invention disclosed herein;

FIG. 8 is a magnified cross sectional view of the extension andretraction arrangement of FIG. 7;

FIGS. 9A, 9B, and 9C comprise side, front, and top plan views of aportion of a trolley structure under the present invention;

FIG. 10 is a perspective view of a manual actuation arrangement;

FIG. 11 is a perspective view of a motorized actuation arrangement;

FIG. 12 is a perspective view of an alternative manual actuationarrangement;

FIG. 13 is a perspective view of a support arm;

FIG. 14 is a perspective view of a braking arrangement;

FIG. 15 is a cross sectional view of an alternative braking arrangementpursuant to the invention disclosed herein;

FIG. 16 is a perspective view of constant force springs for use in anextension and retraction arrangement;

FIG. 17 is a perspective view of an alternative extension and retractionarrangement;

FIG. 18 is a perspective view of another alternative extension andretraction arrangement;

FIG. 19 is a perspective view of still another extension and retractionarrangement under the present invention;

FIG. 20 is an exploded perspective view of an adjustable arm for usepursuant to the invention;

FIG. 21 is a cross sectioned view in side elevation of an extension andretraction arrangement employing the adjustable arm of FIG. 20;

FIG. 22 is a perspective view of an extension and retraction arrangementemploying an alternative articulated arm;

FIG. 23 is a perspective view of an extension and retraction arrangementpursuant to the present invention retained in relation to a slot wallarrangement; and

FIGS. 24A and 24B are perspective views of yet another extension andretraction arrangement under the present invention.

DISCLOSURE OF PREFERRED EMBODIMENTS

The methods and arrangements for the extension and retraction ofsupported articles disclosed herein are subject to a wide variety ofembodiments. However, to ensure that one skilled in the art will be ableto understand and, in appropriate cases, practice the present invention,certain preferred embodiments of the broader invention revealed hereinare described below and shown in the accompanying drawing figures.

While a flat screen monitor is commonly depicted as the article to besupported and while the article is commonly retained relative to a deskor similar structure, it is to be understood that other articles andsupport structures are contemplated within the scope of the invention.Furthermore, extension and retraction can be carried out manually by theuser, by a motorized arrangement, or by any combination thereof.Therefore, before any particular embodiment of the invention isexplained in detail, it must be made clear that the following details ofconstruction and illustrations of inventive concepts are mere examplesof the many possible manifestations of the invention.

Turning more particularly to the drawings, an embodiment of an extensionand retraction arrangement pursuant to the present invention isindicated generally at 10 in FIGS. 1 through 3. In FIG. 1, a supportedarticle, in this example a flat panel computer monitor 12, is shown in afully extended position in relation to a support structure 500, whichcan comprise a desk. The monitor 12 is retained relative to a distalportion of a centrally disposed support arm 54. The support arm 54supports the monitor 12 for extension and retraction through an aperture15 in the support structure 500 by mechanisms described more fullyhereinbelow.

The extension and retraction arrangement 10 has an upper framework 14.An upper flange 26 can be engaged with the upper framework 14 and canoverly the surface of the support structure 500. First and second doors22 and 24 can be pivotally coupled to the upper framework 14 to enable apivoting between the closed configuration shown in FIGS. 1 and 3 and theopen configuration depicted in FIG. 2. An arm aperture 25 can beprovided in either or both of the doors 22 and 24, in this example justthe first door 22, to enable the doors 22 and 24 to reach a fully closedconfiguration even while the monitor 12 and support arm 54 are fullyextended. Advantageously, when the first and second doors 22 and 24 arepivoted to a closed configuration, the aperture 15 in the supportstructure 500 can be effectively sealed, and a generally continuoussurface can be presented, whether below the monitor 12 as in FIG. 1 orabove the monitor 12 as in FIG. 3.

Operation of the first and second doors 22 and 24 can be controlled byany effective means. In certain embodiments, for example, the first andsecond doors 22 and 24 can be spring loaded and latched by a latchingmeans that enables an opening of the first and second doors 22 and 24 bya further depression of the doors 22 and 24 to release the latchingmeans. Alternatively, as will be elaborated upon below, a trigger 88 canenable an automatic opening of the first and second doors 22 and 24 and,additionally or alternatively, a raising of the monitor 12 and thesupport arm 54. Operation of the trigger 88 can be controlled by a lock94 that can be operated by a key 92, a keycard, or any other means.

Use of such an extension and retraction arrangement 10 can begin withthe monitor 12 or other article retained below or within a surface of asupport structure 500. The first and second doors 22 and 24 can beopened, such as by an actuation of the trigger 88. The support arm 54and the retained monitor 12 can then rise through motorization, throughmechanical forces, or, additionally or alternatively, by manualactuation by the user. By means disclosed herein, the monitor 12 andsupport arm 54 can be locked in a fully raised position. Then, the firstand second doors 22 and 24 can, if necessary or desirable, be pivoted toa closed configuration as in FIG. 1. When the monitor 12 or otherarticle is no longer needed, the doors 22 and 24 can be opened and themonitor 12 and support arm 54 can be retracted as in FIG. 2 by anysuitable method including gravity, motorization, mechanical forces,manual actuation, or any combination thereof. Again by means disclosedherein, the monitor 12 and support arm 54 can potentially be locked in aretracted position and the first and second doors 22 and 24 can bemanually or automatically pivoted to a closed configuration as in FIG.3.

An embodiment of an extension and retraction arrangement 10 is depictedapart from the support structure 500 in FIG. 4. There, the extension andretraction arrangement 10 the upper framework 14 can be seen to have aperipheral flange 18 for being retained in relation to a support surface(not shown in FIG. 4) that has an aperture formed therein for receivingthe extension and retraction arrangement 10. A subsurface enclosure 16is fixed to the upper framework 14. The subsurface enclosure 16 definesa protected open inner volume for receiving an article to be retainedwhen the article is in a retracted configuration.

The subsurface enclosure 16 and the upper framework 14 have a sharedopen mouth 20 that can be selectively closed by the pivotally retainedfirst door 22 in combination with the pivotally retained second door 24.One or more apertures 32 can be disposed in a distal portion of thesubsurface enclosure 16 for enabling, among other things, a retrieval ofdebris and a passage of wiring where necessary. Additionally, one ormore wire management apertures 34 can be disposed along a proximalportion of the subsurface enclosure 16 for enabling a passage of wiringand the like. Still further, a removable or pivotable wire managementcover 30 can enable further wiring and other access to the open innervolume of the subsurface enclosure 16. The upper flange 26 can couple tothe upper framework 14 and can overlie an aperture in a support surface.First and second mounting stabilizers 28 can each have a proximalportion fixed to the support surface and, additionally or alternatively,the upper framework 14 and a distal portion fixed to the subsurfaceenclosure 16 for providing stabilizing support thereto.

First and second rails 36 and 38 communicate longitudinally within oralong the subsurface enclosure 16 from adjacent to the distal endthereof to adjacent to the proximal end thereof. The first and secondrails 36 and 38, which are fixed in relation to the subsurface enclosure16 and the upper framework 14, can be formed and fixed in placeseparately. Alternatively, as is shown in FIGS. 4 through 8, the firstand second rails 36 and 38 can be joined with a spine member 40, such asby being unitarily formed therewith as by an extrusion process or thelike or by being fixed thereto.

In either case, a trolley structure 42 can be slidably retained relativeto the first and second rails 36 and 38 for reciprocating movementtherealong between what can be termed an extended disposition as isdepicted in FIG. 4 where the trolley structure 42 is disposed adjacentto the mouth 20 of the subsurface enclosure 16 and the upper framework14 and a retracted disposition where the trolley structure 42 isdisposed adjacent to what can be considered the distal end of thesubsurface enclosure 16. The open inner volume of the subsurfaceenclosure 16 can have a truncated T shape with a head portion of the Tprovided for reception of the article to be supported, such as a monitor12, and the base portion of the T for receiving the first and secondrails 36 and 38 and the spine member 40.

A greater understanding of the trolley structure 42, the first andsecond rails 36 and 38, and the relationship therebetween can be hadwith additional reference to FIGS. 7, 8, and 9A through 9C. The trolleystructure 42 can have a central portion 44 with first and second wingportions 46 and 48 fixed thereto, such as by fasteners 50 or by beingformed integrally therewith. The central portion 44 can have a centrallydisposed alcove 52 with a width W₁ disposed inboard of the first andsecond rails 36 and 38 for receiving a support arm 54 whereby thetrolley structure 42 and the first and second rails 36 and 38 canoperate with a lesser depth D than might otherwise be required.

One exemplary support arm 54 is shown apart in FIG. 13. There, thesupport arm 54 can be seen to have a base portion 136 for being fixed tothe trolley structure 42, such as by mechanical fasteners 56 as in FIG.7, a contoured body portion 142, and a tip portion 138. In this example,the tip portion 138 comprises a sleeve for pivotally retaining a supportplate 144 by use of axle rods 146. The support plate 144 can havethreaded mounting holes 145 therein for enabling a fastening to a flatscreen monitor, such as pursuant to the standardized Video ElectronicsStandards Association Flat Display Mounting Standard for flat panelmonitors.

Each rail 36 and 38 can comprise a side plate 58 with a rigid ventralfin 60 projecting laterally from a ventral side thereof and a rigiddorsal fin 62 projecting laterally from a dorsal side thereof. Aplurality of wheel structures 64 can project inboard from the wingportions 46 and 48 for rolling along one or both of the ventral fin 60and the dorsal fin 62. As FIG. 9C shows, each wheel structure 64 cancomprise an outer wheel 70 rotatably retained relative to an axle 74with a bushing 72 therebetween. While the outer wheels 70 could beformed from a variety of materials, one presently contemplatedembodiment has outer wheels 70 formed from a high strength acetal resin,such as that sold under the trademark DELRIN.

The bushing 72 of each wheel structure 64 can have a head portion forretaining the outer wheel 70 thereon, a body portion for being receivedwithin the outer wheel 70, and a narrowed tip portion for being receivedin an aperture 76 in the wing portion 46 or 48. The tip portion of thebushing 72 can ensure a centering and precise location of the wheelstructure 64 in relation to the aperture 76 and the wing portion 46 or48 in general. Channels 66 and 68 can communicate longitudinally alongthe ventral and dorsal fins 60 and 62 for receiving and engaging thewheels 70 of the wheel structures 64. Each of the outer wheels 70 canhave an arcuate or otherwise contoured profile for engaging acorresponding profile of the channels 66 and 68 thereby to ensure aprecise location and registration of the trolley structure 42 inrelation to the first and second rails 36 and 38.

As previously suggested, the support arm 54 will normally retain anarticle to be supported, such as a monitor or other computer component,to what can be considered the ventral side of the trolley structure 42.As a result, the trolley structure 42 will likely be subjected to atorsion that will tend to press an upper portion of the trolleystructure 42 in a ventral direction while pressing a lower portion ofthe trolley structure 42 in a dorsal direction. To accommodate such atorque most smoothly and effectively, as FIG. 9A shows in relation tothe second wing portion 48, the wing portions 46 and 48 of the trolleystructure 42 can have first and second primary load bearing wheelstructures 64A disposed to the ventral side of the wing portions 46 and48 adjacent to the upper ends thereof and first and second primary loadbearing wheel structures 64A disposed to the dorsal side of the wingportions 46 and 48 adjacent to the lower ends thereof. To maintain thestability of the trolley structure 42 in the event of an oppositetorque, such as might occur where a lifting force is applied thereto, astabilizing wheel structure 64B can be disposed to the dorsal side ofthe wing portions 46 and 48 adjacent to the upper ends thereof and tothe ventral side of the wing portions 46 and 48 adjacent to the lowerends thereof.

Support for the trolley structure 42 and the article retained therebycan be provided by one or more constant force springs 78 and 80. In thisembodiment, each constant force spring 78 and 80 is rotatably retainedrelative to the spine member 40 by an axle 84 with a first end coupledto the spine member 40 and a second end retained relative to alongitudinal fin 82 that projects inboard from the side plate 58 of therail 36 or 38. The axles 84 are separated by a width distance W₂. Theconstant force springs 78 and 80 are shown apart in FIG. 16. Eachconstant force spring 78 and 80 has a distal end fixed to the trolleystructure 42, such as to the alcove portion 52 thereof, by anyappropriate means, such as a mechanical fastener 86, welding, or anyother mechanism.

As shown in FIG. 16, the constant force springs 78 and 80 can comprisetightly coiled wound spring steel with built in curvature. Each turn ofthe springs 78 and 80 can wrap tightly around the next inner turn. Asthe springs 78 and 80 are extended, such as when the trolley 40 andmonitor 12 are lowered, an inherent stress in the springs 78 and 80resists the load at a constant rate thereby ensuring a substantiallyconstant force output. The constant force springs 78 and 80 can beselected to match with the weight of the monitor 12 to be supported. Theconstant force springs 78 and 80 can be calibrated to counterbalance thecombined weight of the trolley 40, support arm 54, and the monitor 12 inan essentially equipoise situation, with a net lifting force thereby totend to raise the monitor 12 automatically, or with a net extensiveforce thereby tending to lower the monitor 12 automatically. Of course,other types and numbers of springs, including compression springs,extension springs, and other types of springs, can be used within thescope of the invention.

Embodiments of the invention can additionally incorporate a means forproviding a braking and cushioning effect at either or both ends oftravel of the trolley 40 and the monitor 12. One such means in depictedin FIGS. 7 and 8 and then alone in FIG. 14 where just a portion of thespine 40 is shown. There, an arcuate braking member 148 has a first endfixed, such as in relation to the spine 40, and a free body portion. Abraking screw 150 is threadedly engaged with the spine 40 to underliethe braking member 148. With this, the braking member 148 willfrictionally engage the trolley structure 42 thereby to slow and controlits travel and, possibly, to prevent an inadvertent lowering of themonitor 12. The degree of braking provided by the braking member 148 canbe adjusted by a rotation of the braking screw 150.

Other braking means are possible pursuant to the invention. For example,an alternative braking arrangement is shown in FIG. 15. There, acompression spring 152 is retained within a spring housing 154, whichcan be formed within or coupled to the spine 40. A projection 156 fromthe trolley structure 42 can project into the spring housing 154 toengage the spring 152 to brake and cushion the travel of the trolleystructure 42 and the retained monitor 12 or other article. A cap member158 can be disposed at a distal end of the spring 152 to ensure apositive engagement with the projection 156, and a stop member 168 canproject from the spring housing 154 into the open inner volume thereofto prevent excessive extension of the spring 152. The initial deflectionof the spring 152 and thus the braking force thereof can be adjusted byan adjustment screw 160 that is rotatably retained relative to an upperportion 162 of the spring housing 154 by a retaining ring 166. Theadjustment screw 160 can be threadedly engaged with an adjustment nut164, which can be separately or integrally formed with the springhousing 154. Under such an arrangement, the spring 152 can provide acushioning and braking effect as the projection 156 engages the spring152.

Referring again to FIG. 4, the embodiment of the extension andretraction arrangement 10 depicted therein can be manually operated. Thefirst and second doors 22 and 24 can be spring-loaded. Their opening canbe triggered by any appropriate method, such as by a pressing thereon orby operation of a switch, such as the trigger 88 or by a remote control(not shown in this drawing). The trolley structure 42 and the articleretained thereby, such as a computer monitor, can automatically extendwhen the doors 22 and 24 are opened. When the article is to be returnedto a storage configuration, a user can simply push the article downwardto cause the trolley structure 42 to slide longitudinally along therails 36 and 38.

The operation and movement of the large and small doors 22 and 24 andthe trolley structure 42 can be controlled by a manual actuatingarrangement 90, which can be understood with combined reference to FIGS.7, 8, and 10. The manual actuating arrangement 90 can be controlled bythe trigger 88. More particularly, a lateral axle 100 can be rotated bya pivoting of the trigger 88. An actuating rod 132 can have a first endcoupled to the lateral axle 100 and a second end coupled to a first legof a pivotally retained L-shaped actuator 133. An engaging member 135with locking tips 137 projecting therefrom can be pivotally coupled to asecond leg of the L-shaped actuator 133. The large and small doors 22and 24 can have spring-loaded disc portions 96 and 98 operablyassociated therewith, such as at each end thereof. With this, asufficient turning of the lateral axle 100 will disengage the lockingtips 137 from the first and second doors 22 and 24 thereby allowing thedoors 22 and 24 to open. Each door 22 and 24 can have a frictionaldamper associated therewith to ensure a smooth opening process.

Additionally, a vertical locking rod 102 can be coupled to the lateralaxle 100 by a pivot rod 104 such that the vertical locking rod 102 canbe reciprocated upwardly and downwardly by a rotation of the lateralaxle 100. The vertical locking rod 102 can have a pivotally retainedproximal L-shaped actuator 108 with an engaging tip 112 proximallycoupled thereto and a pivotally retained distal L-shaped actuator 110with an engaging tip 114 distally coupled thereto. Also, looking againto FIGS. 7 and 8, the trolley structure 42 can have a locking projection116 projecting dorsally therefrom.

The trolley structure 42 can be selectively locked in a retractedconfiguration by an engagement of the engaging tip 114 of the distalL-shaped actuator 110 with the locking projection 116. Similarly, thetrolley structure 42 can be selectively locked in an extendedconfiguration by an engagement of the engaging tip 112 of the proximalL-shaped actuator 108 with the locking projection 116. The trolleystructure 42 can be released from each position by a simple actuation ofthe trigger 88 to cause the respective tip 112 or 114 to pivot out ofengagement with the locking projection 116. The lock 94, which can beoperated by a key 92 or any other effective arrangement, can selectivelyprevent operation of the trigger 88.

Use of an embodiment of a non-motorized extension and retractionarrangement 10 as in FIG. 4 with a manual actuation arrangement 90 as inFIG. 10 can be initiated by a pivoting or other actuation of the trigger88. With a sufficient pivoting of the trigger 88, the actuating rod 132can induce a pivoting of the L-shaped actuator 133 thereby to releasethe first and second doors 22 and 24 as the locking tips 137 are drawnout of engagement therewith. The spring-loaded disc portions 96 and 98can then smoothly pivot the first and second doors 22 and 24 to an openconfiguration. Simultaneously, the rotation of the lateral axle 100 canproduce a vertical displacement of the vertical locking rod 102 therebyto pivot the engaging tip 114 of the distal L-shaped member 110 out ofengagement with the locking projection 116 of the trolley structure 42.The trolley structure 42 is thus released from its retracted position.

Where the constant force springs 78 and 80 are calibrated to produce anet lifting force, the trolley 40, support arm 54, and the monitor 12can then automatically rise to an extended position as in FIG. 1. Themeans for providing a braking and cushioning effect, whether in the formof an arcuate braking member 148, a compression spring 152, or any otherform, can enable a smooth and controlled stopping of the travel of thetrolley structure 42 and the retained monitor 12 or other article. Theengaging tip 112 of the proximal L-shaped actuator 108 can then engagethe locking projection 116 of the trolley structure 42 thereby lockingthe monitor 12 and the trolley structure 42 in an extendedconfiguration.

The first and second doors 22 and 24 can then be adjusted to a closedconfiguration as in FIG. 1 to prevent debris from passing through theaperture 15 in the support structure 500 and to achieve a finishedappearance. It will be noted that providing first and second doors 22and 24 as compared to just a single door can be considered to beadvantageous for a number of reasons. For example, with first and seconddoors 22 and 24, the monitor 12, and consequently the support arm 54 andthe trolley 42, can be raised to a reduced height to gain clearancerelative to the doors 22 and 24 than would be required if just a singledoor were provided. Since the height to which the monitor 12 must beraised directly affects the required length of the first and secondrails 36 and 38 and the subsurface enclosure in general 16, theprovision of first and second doors 22 and 24 enables the extension andretraction arrangement 10 to be rendered more efficient and compact.Furthermore, the first and second doors 22 and 24 enable the armaperture 25, and thus the support arm 54, to be centrally disposed inrelation to the aperture 15 and the extension and retraction arrangement10.

When the monitor 12 is to be lowered, the trigger 88 can again beactuated to reopen the doors 22 and 24 and to release the engaging tip112 of the proximal L-shaped actuator 108. The monitor 12, support arm54, and the trolley structure 42 can be pressed to a retracted positionand locked there by the engaging tip 114 of the distal L-shaped actuator110. The doors 22 and 24 can be pressed closed and retained there by anengagement with the locking tips 137.

A variation of the manual actuation arrangement 90 is shown in FIG. 12.There, engaging tips 112 and 114 are again provided for selectivelyengaging and retaining the locking projection 116 of the trolleystructure 42. However, the L-shaped actuators 108 and 110 insteadcomprise rotatably retained disc-shaped actuators 108 and 110.Furthermore, a pivot gearing arrangement 106 is instead employed toinduce a reciprocation of the vertical locking rod 102 in response to anactuation of the trigger 88.

As the embodiment of FIG. 5 makes clear, the extension and retractionarrangement 10 can alternatively be motorized. An example of a motorizeddrive and actuating arrangement 140 is shown in FIG. 11. A drive motor118 can be fixed relative to the trolley structure while a rack gear 122can be fixed relative to the spine 40 and the first and second rails 36and 38 shown, for example, in FIG. 7. A pinion gearing arrangement 120can drivingly engage the drive motor 118 with the rack gear 122. Asecondary motor 124 can be drivingly associated with a lateral rod 130by a gearing arrangement 128. The lateral rod 130 can in turn bedrivingly engaged with door driving rods 132 by a worm gear arrangement134. The door driving rods 132 can engage the first door 22 by a geararrangement 126 between the door driving rods 132 and geared discportions 96 of the first door 22. Similarly, the door driving rods 132can engage the second door 24 by a gear arrangement 125 between the doordriving rods 132 and geared disc portions 98 of the second door 24.Constant force springs 78 and 80 as shown in FIG. 7 may or may not beincluded to provide a counterbalancing force in relation to the trolleystructure 42, the monitor 12, and the support arm 54.

A lock 94 and key 92 combination can enable access and control of theextension and retraction arrangement 10. Alternatively or additionally,as shown in relation to the alternative embodiment of FIG. 17, accessand control of the extension and retraction arrangement 10 could becontrolled by a card reader 172 in combination with an access card 170.The access card 170 could be of any suitable type including, by way ofexample, a dedicated security card, an identification card, a creditcard, a purchased card, or any other type of access card 170. Stillfurther, access and control could be had by operation of a remotecontrol unit 174 in combination with a receiver 176 as is also shown inFIG. 11.

Actuation of the motorized drive and actuating arrangement 140 of FIG.11 can induce the secondary motor 124 into operation thereby to rotatethe lateral rod 130 with a resultant rotation of the door driving rods132 and an opening of the doors 22 and 24 as the disc portions 96 and 98are driven by the gearing arrangements 126 and 125. Simultaneously with,before, or after, the opening of the doors 22 and 24, the drive motor118 can be induced into operation thereby to cause it, the trolleystructure 42, and the retained monitor 12 to climb the rack gear 122until an extended disposition is reached as may be sensed by an upperlimit switch 127 or other means. The first and second doors 22 and 24can then be closed by the secondary motor 124.

When the monitor 12 or other article is to be retracted, the lock 94 andkey 92, the card reader 172 and access card 170, the trigger 88, theremote control unit 174 and receiver 176, or any other means can beemployed to induce the secondary motor 124 into operation to open thedoors 22 and 24. The drive motor 118 can then be actuated to propel thetrolley structure 42, the monitor 12, and the support arm 54 to aretracted configuration. The doors 22 and 24 can then be closed byoperation of the secondary motor. Of course, one skilled in the artwould find it readily obvious and within the scope of the invention toemploy a single motor or more than two motors for opening the doors 22and 24 and raising and lowering the trolley structure 42.

An alternative extension and retraction arrangement is again indicatedat 10 in FIG. 18. The extension and retraction arrangement 10 has asupport base 184 relative to which a pair of cylindrical support rods186 and 188 are mounted in parallel spaced orientation relative to oneanother. Distal ends of the cylindrical support rods 186 and 188 aremounted on a lower support bracket 190. A trolley structure 42 isslidably engaged with the support rods 186 and 188.

The trolley structure 42 in this embodiment includes opposing bushings192 and 194 that slide along the support rods 186 and 188. Bearings196,198 provide smooth gliding engagement between the bushings 192 and194 and the support rods 186 and 188. Threaded mounting holes 145 areagain formed in the trolley structure 42 in accordance with the VideoElectronics Standards Association Flat Display Mounting Standard forflat panel monitors. Constant force springs 78 and 80 are rotatablyretained relative to the support base 184 and have distal ends connectedto the trolley structure 42.

To prevent damage to the monitor 12 as it reaches an extended position,rubber o-rings 200 and 202 mounted on the upper or proximal ends of thesupport rods 186 and 188 provide shock absorption for the trolleystructure 42. A lock 94 and key 92 combination or other means cancontrol access and operation of the extension and retraction arrangement10 to prevent unauthorized access to the monitor 12 or other supportedarticle. The lock 94 can prevent rotation of the lateral axle 100 untilthe key 92 or other means is actuated.

As shown in FIG. 17, the raising and lowering of the trolley structure42 can be driven by a motor 182 that drives a pinion gear 180 along arack gear 178. The rack gear 178 can be disposed along a support rod 188or otherwise disposed, such as along a subsurface enclosure (not shown).As previously described, access and control can additionally becontrolled by a card reader 172 and access card 170 and, additionally oralternatively, a remote control unit 174 and receiver 176. Such anextension and retraction arrangement 10 can be employed with or withoutconstant force springs 78 and 80.

With reference to FIG. 19, one sees that a braking arrangement can againbe provided. The braking arrangement can again include an arcuatebraking member 148 and a braking screw 150 for adjusting the brakingforce to be applied. The braking member 148 can have a first end fixedin relation to the support base 184 and a free body portion.

Extension and retraction arrangements 10 can be supplied with a supportstructure 500, such as the desk in FIGS. 1 through 3, as originalequipment. Alternatively, extension and retraction arrangements 10 canbe supplied in retrofit kit form. As one can perceive from FIG. 6, sucha kit could include the extension and retraction arrangement 10,mounting fasteners 35, and a template 33 for cutting an aperture 15 in asupport structure 500 in which it is to be installed. With an extensionand retraction arrangement 10 installed in relation to a supportstructure, whether before or after sale to the ultimate consumer, amonitor 12 can be readily mounted to the support arm 54. The supportstructure 500, the extension and retraction arrangement 10, and themonitor 12 can be sold integrated together. Alternatively, the monitor12 and an extension and retraction arrangement 10 can be sold as apackage.

With reference to FIGS. 20 and 21, an extension and retractionarrangement 10 is depicted that not only extends and retracts anarticle, such as a monitor 12, but also enables an adjustment of theposition, orientation, and location of the monitor 12 by use of a springbalanced arm arrangement 205. The spring balanced arm arrangement 205can have an arm 204 that can be pivotally coupled to the trolleystructure 42 at a proximal pivot axis 206. The monitor 12 can bepivotally coupled to the arm 204 at a distal pivot axis 208. The arm 204can include first and second arm portions 204A and 204B and can bebalanced by one or more springs 214. Additionally, the arm 204 canrotate about a vertical axis relative to the support structure 500 by arotation of a pivot rod 210 that projects from the proximal pivot axis206 and is received into a pivot aperture 212 in the trolley structure42.

In FIG. 22, the spring balanced arm 205 can be articulated with a firstarm 216 pivotally coupled at a proximal end to the trolley structure 42and a distal end pivotally coupled to a proximal end of a second arm218. The monitor 12 can be pivotally coupled to the monitor 12 by amonitor mounting bracket 220. The first arm 216 can be formed by spacedfirst and second arm portions 204A and 204B, and the second arm 218 canbe pivoted to be disposed inboard of the first and second arm portions204A and 204B to enable a most compact storage of the spring balancedarm 205.

As noted previously, extension and retraction arrangements 10 under thepresent invention can be employed relative to numerous different typesof support structures 500, not only desks. For example, turning to FIG.23, an extension and retraction arrangement 10 is retained relative to asupport structure 500 comprising a slot wall arrangement. The slot wallarrangement can have a wall portion 502 and, possibly, a desk portion504. The subsurface enclosure 16 and the extension and retractionarrangement 10 in general can be secured relative to a slot 222 in thewall portion 502 to enable the monitor 12 and support arm 54 to beextended from the subsurface enclosure 16, possibly through the deskportion 504. Alternatively, the subsurface enclosure 16 of the extensionand retraction arrangement 10 can be disposed within a wall portion 502,which may or may not be a slot wall. In certain cases, for example, thewall portion 502 can comprise a typical office partition wall or anyother type of wall.

Yet another embodiment of the extension and retraction arrangement 10 isdepicted in FIGS. 24A and 24B. There, a computer central processing unit224 is retained within the subsurface enclosure 16 for interaction withthe monitor 12, a keyboard 230, and any further computer components thatmay be required. Furthermore, one or more computer drive units 226 canbe incorporated into the extension and retraction arrangement 10, suchas in relation to the upper framework 14 as in FIGS. 24A and 24B. Withthis, the extension and retraction 10 arrangement could house oressentially comprise a self-enclosed computer system.

In certain practices of the invention, a keyboard 230 can additionallyor alternatively be retained for extension and retraction. As shown inFIGS. 24A and 24B, for example, a keyboard 230 can be retained relativeto the support arm 54, and thus relative to the trolley structure 42(not shown in FIGS. 24A and 24B) by a keyboard cradle 228. The keyboardcradle 228 could be fixed in relation to the support arm 54 or pivotableby use of a pivot arrangement 232. The keyboard 230 can be used whileretained in relation to the keyboard cradle 228, or it can be removableas in FIG. 24B.

With certain details and embodiments of the present invention forextension and retraction arrangements disclosed, it will be appreciatedby one skilled in the art that numerous changes and additions could bemade thereto without deviating from the spirit or scope of theinvention. This is particularly true when one bears in mind that thepresently preferred embodiments merely exemplify the broader inventionrevealed herein. Accordingly, it will be clear that those with majorfeatures of the invention in mind could craft embodiments thatincorporate those major features while not incorporating all of thefeatures included in the preferred embodiments.

Therefore, the following claims are intended to define the scope ofprotection to be afforded to the inventor. Those claims shall be deemedto include equivalent constructions insofar as they do not depart fromthe spirit and scope of the invention. It must be further noted that aplurality of the following claims express certain elements as means forperforming a specific function, at times without the recital ofstructure or material. As the law demands, these claims shall beconstrued to cover not only the corresponding structure and materialexpressly described in this specification but also all equivalentsthereof.

1. An extension and retraction arrangement for enabling an adjustment ofa supported article from a retracted configuration to an extendedconfiguration, the extension and retraction arrangement comprising: atrolley structure; a support arm for retaining an article to besupported in relation to the trolley structure wherein the support armhas a proximal portion coupled to the trolley structure and a distalportion for coupling to the article to be supported; an elongate supportarrangement with a proximal end, a distal end, and a body portionwherein the elongate support arrangement comprises a first elongatesupport structure and a second elongate support structure disposed inspaced relation relative to the first elongate support structure whereineach of the first and second support structures has a dorsal side and aventral side; and a means for supporting the trolley structure for axialextension and retraction along the body portion of the elongate supportarrangement from adjacent to the distal end to adjacent to the proximalend of the elongate support arrangement wherein the trolley structure isslidably associated with the first and second elongate supportstructures, wherein the proximal portion of the support arm is disposedinboard of the first and second elongate support structures, and whereinthe trolley structure has first and second portions slidably associatedwith the first and second elongate support structures and a centrallydisposed alcove that is recessed in a dorsoventral direction in relationto the first and second portions and that is recessed between the firstand second elongate support structures and wherein the proximal portionof the support arm is coupled to the centrally disposed alcove of thetrolley structure; whereby the article to be supported and the trolleystructure can be retained in a retracted configuration with the trolleystructure disposed adjacent to the distal end of the elongate supportarrangement and whereby the article and the trolley structure can beretained in an extended configuration with the trolley structuredisposed adjacent to the proximal end of the elongate supportarrangement.
 2. The extension and retraction arrangement of claim 1further comprising a framework disposed adjacent to the proximal end ofthe elongate support arrangement wherein the framework has a centrallydisposed aperture wherein the article to be supported projects at leastpartially through the aperture in the framework when the trolleystructure is disposed adjacent to the proximal end of the elongatesupport arrangement.
 3. The extension and retraction arrangement ofclaim 2 further comprising at least one door with an open position and aclosed position for at least partially closing the aperture in theframework.
 4. The extension and retraction arrangement of claim 3wherein there are first and second doors pivotally coupled in relationto the framework.
 5. The extension and retraction arrangement of claim 4wherein the first door is larger than the second door.
 6. An extensionand retraction arrangement for enabling an adjustment of a supportedarticle from a retracted configuration to an extended configuration, theextension and retraction arrangement comprising: a trolley structure; asupport arm for retaining an article to be supported in relation to thetrolley structure wherein the support arm has a proximal portion, adistal portion, and a body portion; an elongate support arrangement witha proximal end, a distal end, and a body portion; a means for supportingthe trolley structure for axial extension and retracting along the bodyportion of the elongate support arrangement from adjacent to the distalend to adjacent to the proximal end of the elongate support arrangement;a framework disposed adjacent to the proximal end of the elongatesupport arrangement wherein the framework has a centrally disposedaperture wherein the article to be supported projects through theaperture in the framework and the body portion of the support arm passesthrough the aperture in the framework when the trolley structure isdisposed adjacent to the proximal end of the elongate supportarrangement; and at least one door with an open position and a closedposition for at least partially closing the aperture in the frameworkand an aperture in the at least one door for accommodating the bodyportion of the support arm and for enabling a closure of the at leastone door not only while the trolley structure is in a retractedconfiguration but also while the trolley structure is in an extendedconfiguration with the body portion of the support arm projectingthrough the aperture in the at least one door; whereby the article to besupported and the trolley structure can be retained in a retractedconfiguration with the trolley structure disposed adjacent to the distalend of the elongate support arrangement and whereby the article and thetrolley structure can be retained in an extended configuration with thetrolley structure disposed adjacent to the proximal end of the elongatesupport arrangement.
 7. The extension and retraction arrangement ofclaim 6 further comprising a means for assisting the trolley structurein traveling in relation to the elongate support arrangement comprisingat least one constant force spring.
 8. The extension and retractionarrangement of claim 7 wherein the at least one constant force springhas a body portion retained adjacent to the proximal end of the elongatesupport arrangement and an end portion coupled to the trolley structure.9. The extension and retraction arrangement of claim 7 wherein the meansfor retaining an article to be supported in relation to the trolleystructure comprises a means for retaining a flat screen monitor.
 10. Theextension and retraction arrangement of claim 9 further comprising aflat screen monitor retained by the means for retaining a flat screenmonitor.
 11. An extension and retraction arrangement for enabling anadjustment of a supported article from a retracted configuration to anextended configuration, the extension and retraction arrangementcomprising: a trolley structure; a means for retaining an article to besupported in relation to the trolley structure; an elongate supportarrangement with a proximal end, a distal end, and a body portion; ameans for supporting the trolley structure for axial extension andretraction along the body portion of the elongate support arrangementfrom adjacent to the distal end to adjacent to the proximal end of theelongate support arrangement; a framework disposed adjacent to theproximal end of the elongate support arrangement wherein the frameworkhas a centrally disposed aperture wherein the article to be supportedprojects at least partially through the aperture in the framework whenthe trolley structure is disposed adjacent to the proximal end of theelongate support arrangement; at least one door with an open positionand a closed position for at least partially closing the aperture in theframework; a means for enabling a selective locking of the at least onedoor in a closed position; and a subsurface enclosure with an open innervolume wherein the elongate support arrangement is disposed within thesubsurface enclosure whereby the trolley structure and the article to besupported can be retained within the open inner volume of the subsurfaceenclosure when the article to be supported and the trolley structure arein a retracted configuration; whereby the article to be supported andthe trolley structure can be retained in a retracted configuration withthe trolley structure disposed adjacent to the distal end of theelongate support arrangement and whereby the article and the trolleystructure can be retained in an extended configuration with the trolleystructure disposed adjacent to the proximal end of the elongate supportarrangement.
 12. The extension and retraction arrangement of claim 11wherein the means for retaining an article in relation to the trolleystructure comprises a support arm.
 13. The extension and retractionarrangement of claim 12 wherein the support arm has a proximal portioncoupled to the trolley structure and a distal portion for coupling tothe article to be supported.
 14. The extension and retractionarrangement of claim 13 wherein the elongate support arrangementcomprises a first elongate support structure and a second elongatesupport structure disposed in spaced relation relative to the firstelongate support structure, wherein the trolley structure is slidablyassociated with the first and second elongate support structures,wherein the proximal portion of the support arm is disposed inboard ofthe first and second elongate support structures.
 15. An extension andretraction arrangement for enabling an adjustment of a supported articlefrom a retracted configuration to an extended configuration, theextension and retraction arrangement comprising: a trolley structure; ameans for retaining an article to be supported in relation to thetrolley structure; an elongate support arrangement with a proximal end,a distal end, and a body portion; a means for supporting the trolleystructure for axial extension and retraction along the body portion ofthe elongate support arrangement from adjacent to the distal end toadjacent to the proximal end of the elongate support arrangement; and ameans for providing a braking effect on the trolley structure inrelation to the elongate support arrangement and a means for adjustingthe braking effect provided by the means for providing a braking effectwherein the means for providing a braking effect comprises a flexiblearcuate braking member retained for creating a frictional engagementbetween the trolley structure and a frame structure disposed adjacent toan end of the elongate support arrangement and wherein the means foradjusting the braking effect provided by the means for providing abraking effect comprises a threaded member operably associated with thearcuate braking member for adjusting a braking force exhibited by thearcuate braking member; whereby the article to be supported and thetrolley structure can be retained in a retracted configuration with thetrolley structure disposed adjacent to the distal end of the elongatesupport arrangement and whereby the article and the trolley structurecan be retained in an extended configuration with the trolley structuredisposed adjacent to the proximal end of the elongate supportarrangement, whereby the frame structure has a centrally disposedaperture for the means for retaining an article to extend outwardlythereof for displaying the article.
 16. An extension and retractionarrangement for enabling an adjustment of a supported article from aretracted configuration to an extended configuration, the extension andretraction arrangement comprising: a trolley structure; a means forretaining an article to be supported in relation to the trolleystructure; an elongate support arrangement with a proximal end, a distalend, and a body portion; a means for supporting the trolley structurefor axial extension and retraction along the body portion of theelongate support arrangement from adjacent to the distal end to adjacentto the proximal end of the elongate support arrangement; and a means forproviding a braking effect on the trolley structure in relation to theelongate support arrangement and a means for adjusting the brakingeffect provided by the means for providing a braking effect wherein themeans for providing a braking effect comprises a compression spring forbeing interposed between the trolley structure and a frame structuredisposed adjacent to an end of the elongate support arrangement; wherebythe article to be supported and the trolley structure can be retained ina retracted configuration with the trolley structure disposed adjacentto the distal end of the elongate support arrangement and whereby thearticle and the trolley structure can be retained in an extendedconfiguration with the trolley structure disposed adjacent to theproximal end of the elongate support arrangement, whereby the framestructure has a centrally disposed aperture for the means for retainingan article to extend outwardly thereof for displaying the article. 17.The extension and retraction arrangement of claim 16 further comprisinga means for assisting the trolley structure in traveling in relation tothe elongate support arrangement.
 18. The extension and retractionarrangement of claim 16 wherein the compression spring is disposedwithin a spring housing and wherein the trolley structure has aprojection for projecting into the spring housing and engaging thecompression spring.
 19. The extension and retraction arrangement ofclaim 18 wherein the means for adjusting the braking effect provided bythe means for providing a braking effect comprises a means for adjustingan initial compression of the compression spring.
 20. An extension andretraction arrangement for enabling an adjustment of a supported articlefrom a retracted configuration to an extended configuration, theextension and retraction arrangement comprising: a trolley structure; ameans for retaining an article to be supported in relation to thetrolley structure wherein the article is a flat screen monitor; anelongate support arrangement with a proximal end, a distal end, and abody portion; a means for supporting the trolley structure for axialextension and retraction along the body portion of the elongate supportarrangement from adjacent to the distal end to adjacent to the proximalend of the elongate support arrangement; a subsurface enclosure with anopen inner volume wherein the elongate support arrangement is disposedwithin the subsurface enclosure and further comprising; a means forretaining a computer central processing unit within the subsurfaceenclosure, including during axial extension of the trolley structure;and a computer drive unit retained adjacent to the proximal end of theelongate support arrangement; whereby the article to be supported andthe trolley structure can be retained in a retracted configuration withthe trolley structure disposed adjacent to the distal end of theelongate support arrangement and whereby the article and the trolleystructure can be retained in an extended configuration with the trolleystructure disposed adjacent to the proximal end of the elongate supportarrangement.
 21. The extension and retraction arrangement of claim 20further comprising a support structure with a surface and a means forretaining the elongate support arrangement in relation to the supportstructure with the proximal end of the elongate support arrangement inproximity to the surface of the support structure.
 22. The extension andretraction arrangement of claim 21 further comprising an aperture in thesurface of the support structure wherein the proximal end of theelongate support arrangement is aligned with the aperture in the surfaceof the support structure.
 23. The extension and retraction arrangementof claim 21 wherein the support structure comprises a desk.
 24. Theextension and retraction arrangement of claim 21 wherein the supportstructure comprises a wall segment.
 25. The extension and retractionarrangement of claim 20 wherein the means for retaining an article to besupported in relation to the trolley structure includes an arm with aproximal portion pivotally coupled in relation to the trolley structure.26. An extension and retraction arrangement for enabling an adjustmentof a supported article from a retracted configuration to an extendedconfiguration, the extension and retraction arrangement comprising: atrolley structure; a means for retaining an article to be supported inrelation to the trolley structure; an elongate support arrangement witha proximal end, a distal end, and a body portion; a means for supportingthe trolley structure for axial extension and retraction along the bodyportion of the elongate support arrangement from adjacent to the distalend to adjacent to the proximal end of the elongate support arrangement;and a subsurface enclosure with an open inner volume wherein theelongate support arrangement is disposed within the subsurface enclosurewhereby the trolley structure and the article to be supported can beretained within the open inner volume of the subsurface enclosure whenthe article to be supported and the trolley structure are in a retractedconfiguration wherein the subsurface enclosure has a T-shaped crosssection wherein the elongate support arrangement and the trolleystructure are substantially disposed in a base portion of the T-shapeand wherein a head portion of the T-shape is provided for slidablyhousing the article to be supported; whereby the article to be supportedand the trolley structure can be retained in a retracted configurationwith the trolley structure disposed adjacent to the distal end of theelongate support arrangement and whereby the article and the trolleystructure can be retained in an extended configuration with the trolleystructure disposed adjacent to the proximal end of the elongate supportarrangement.
 27. An extension and retraction arrangement comprising: atrolley structure; a support arm with a proximal portion coupled to thetrolley structure and a distal portion for retaining an article to besupported; an elongate support arrangement with a proximal end, a distalend, and a body portion; a subsurface enclosure with an open innervolume, a proximal portion, and a distal portion wherein the elongatesupport arrangement is disposed within the subsurface enclosure wherebythe trolley structure and the article to be supported can be retainedwithin the open inner volume of the subsurface enclosure when thearticle to be supported and the trolley structure are in a retractedconfiguration; a means for supporting the trolley structure for axialextension and retraction along the body portion of the elongate supportarrangement from adjacent to the distal end to adjacent to the proximalend of the elongate support arrangement; a framework disposed adjacentto the proximal end of the elongate support arrangement wherein theframework has a centrally disposed aperture; a keyboard cradle forretaining a keyboard in relation to the trolley structure; and wherebythe article to be supported and the trolley structure can be retained ina retracted configuration with the trolley structure disposed adjacentto the distal end of the elongate support arrangement and whereby thearticle and the trolley structure can be retained in an extendedconfiguration with the trolley structure disposed adjacent to theproximal end of the elongate support arrangement and with the article tobe supported projecting at least partially through the aperture in theframework, therein the support arm extends through the aperture of theframework for displaying the article.
 28. The extension and retractionarrangement of claim 27 further comprising a flat screen monitor forbeing retained by the support arm.
 29. The extension and retractionarrangement of claim 27 further comprising at least one door with anopen position and a closed position for at least partially closing theaperture in the framework.
 30. The extension and retraction arrangementof claim 27 further comprising at least one constant force spring forassisting the trolley structure in traveling in relation to the elongatesupport arrangement.
 31. The extension and retraction arrangement ofclaim 27 further comprising a computer drive unit retained adjacent tothe proximal end of the elongate support arrangement.
 32. The extensionand retraction arrangement of claim 27 further comprising a means forretaining a computer central processing unit within the subsurfaceenclosure.
 33. The extension and retraction arrangement of claim 27further comprising a plurality of threaded mounting holes formed in thetrolley structure in accordance with the Video Electronics StandardsAssociation Flat Display Mounting Standard for flat panel monitors.